1. Field of the Invention
This invention relates to new and improved method and apparatus for non-invasively detecting the gas-liquid interfaces and respective liquid and gas segments, in an air-segmented liquid stream flowing in a conduit, and for non-invasively determining the respective volumes of the liquid segments of said stream.
2. Description of the Prior Art
Although a number of methods and apparatus are known for detecting a variety of the flow and/or segment arrangement and number characteristics of air-segmented liquid streams flowing in conduits, the same usually require the location of detecting devices within the flow conduit, and are unsuitable for use in continuous flow automated analysis systems. More specifically, it will be appreciated that the presence of a detecting device in the flow conduit obstructs fluid flow in the conduit and degrades "wash" or causes contamination between successive segments. In addition, locating the detecting means in the flow conduit presents serious manufacturing problems, especially in those instances wherein internal diameter of the conduit is small; also, the calibration, relocation, and/or replacement of such detecting device can become particularly difficult. Too, and depending upon the chemical nature of the segmented stream liquid, chemical reaction between the liquid(s) under analysis and the detecting device can occur.
In addition, and although non-invasive methods and apparatus as above are known, they generally require the use of relatively sophisticated, expensive, and, in many instances, not particularly reliable components, which detract markedly from the overall value of those methods and apparatus, and especially in instances wherein the same are applied to automated biomedical analysis devices wherein particularly high standards of reliability must, of necessity, be met.